Collet Comprising a Seal

ABSTRACT

A collet includes a plurality of clamping jaws movable relative to one another, at least one recess provided in one of mutually facing side faces of adjacent clamping jaws, and a spring inserted into each recess and supporting the adjacent clamping jaws resiliently relative to one another, and a seal sealing the gap between two side faces of adjacent clamping jaws, with the seal having a fastening portion engaging in the at least one recess.

The invention relates to a guide clamp or collet. In particular, theinvention relates to a collet having a plurality of clamping jaws whichare movable with respect to one another, at least one recess provided inone of the mutually facing side faces of adjacent clamping jaws, and ineach case a spring inserted into a recess which resiliently loads theadjacent clamping jaws with respect to one another.

Collets of this kind are known from DE 20 2013 010 357 U1, DE 10 2014018 695 B4, DE 93 20 515 U1 and DE 19 07 956 B2, for example.

A problem with all known collets is that during machining of workpieces,chips can enter the gaps and contact surfaces of the particular collet.This leads to functional restrictions by blocking the freedom ofmovement of the clamping jaws, insufficient concentricity and changedalignment of the workpiece, increased wear to the collet, and reducedclamping forces.

This problem is particularly prevalent in longitudinal turning machines,as machining on these machines takes place in the immediate vicinity ofthe collet. A particularly serious issue is the production of very finechips which build up and settle in narrow gaps, undercuts, blind holes,etc.

It is therefore the object of the invention to produce a collet whichretains its functionality despite the circumstances arising specificallyin longitudinal turning machines and the influence of chips.

This object is achieved according to the invention by the collet havingthe features of claim 1. The dependent claims describe advantageousembodiments of the invention.

The basic concept of the invention is to introduce a seal into each gapformed by two adjacent clamping jaws, which gap, for fastening to thecollet, uses the recesses that are already provided in the clamping jawsfor receiving the springs. The seal is in particular made of a resilientmaterial. In this case, the function of the present springs remainsintact, as although the seal engages in the recess, as a hollow cylinderit accommodates the spring without impairment. According to aparticularly preferred embodiment, the seal even replaces the spring, asthe fastening portion is designed as a spring or a resilient cylinderthat is inserted into the recess.

According to the invention, a collet is therefore provided which has aplurality of clamping jaws which are movable with respect to oneanother, at least one recess provided in one of the mutually facing sidefaces of adjacent clamping jaws, in each case a spring inserted into arecess which resiliently loads the adjacent clamping jaws with respectto one another, and in each case a seal sealing the gap between two sidefaces of adjacent clamping jaws, said seal having in each case afastening portion that engages in the at least one recess of a sideface.

The fastening portion of the seal is preferably designed as a hollowcylinder accommodating the spring. This embodiment makes it possible, ina particularly simple manner, to retrofit existing clamping jaws withthe seal without further adaptations being necessary. The existingsprings are simply inserted into the fastening portion, designed as ahollow cylinder of the seals and can perform their function withoutbeing impeded by the seal.

Alternatively, it can preferably be the case that the fastening portionitself is designed as a spring. In the case of retrofitting existingclamping jaws, this would therefore mean that existing springs can beexchanged for the preferably designed seals according to the invention,as the fastening portion formed in one piece with the seal is designedas a spring.

On the other hand, a simple, but highly advantageous embodiment isachieved if the fastening portion is designed as a resilient cylinder.This fastening portion can be readily inserted into the conventionallyprovided recesses of the clamping jaws. The resilient cylinder assumesthe function of a fastening element of the seal on a clamping jaw or onadjacent clamping jaws and also, due to its resilience, the function ofa spring element which resiliently loads the clamping jaws with respectto one another.

The resilient cylinder can comprise one or more (resilient) structureswhich extend radially from the cylinder and are used to anchor thecylinder and therefore the seal in the recesses of the clamping jaws.These structures rest in the recess against the wall of the recess. Forexample, these structures may, in a circular cylinder, be designed asrings extending from the surface of the cylinder.

The outer contour of the seal preferably corresponds to the outerprofile of the side faces of the clamping jaws, such that chips thatoccur during machining cannot enter the gap between the clamping jaws.

More preferably, the seal fully fills the gap between two side faces ofadjacent clamping jaws. Due to this preferred embodiment, the seal canbe produced very easily while maintaining tight tolerances. In addition,connection of the fastening portion as an integral component of the sealover the entire surface is also advantageous with regard to the evendistribution of forces occurring during use if the seal is designed overthe entire surface.

Alternatively, it is also possible for the outer contour of the seal tobe connected to the fastening portion by means of connecting parts. Thisembodiment has the advantage that only a small amount of material needsto be inserted between the clamping jaws as required for sealing the gapand does not need to be overcome in the event of a relative movement ofthe jaws with respect to one another.

This is particularly advantageous when the seal comprises a sealing lipextending from the plane of the seal. The sealing lip is particularlypreferably arranged on the edge of the seal and specifically follows theouter contour of the seal.

The fastening portion and/or the sealing lip extend in particular onboth sides of the plane of the seal, so that the seal is particularlypreferably mirror-symmetric with respect to the gap plane between theclamping jaws. If the seal therefore comprises two opposing fasteningportions, said portions engage in or are inserted into opposite recessesof the opposite side faces of adjacent clamping jaws. Sealing lipsextending on both sides of the seal are therefore supported on theopposing side faces of adjacent clamping jaws.

The collet according to the invention comprises preferably threeclamping jaws.

Finally, it appears to be advantageous for the seal to be made inparticular of an elastomer material and specifically to be produced byinjection molding or 3D printing.

The invention is explained in greater detail in the following withreference to a particularly preferred embodiment which is shown highlyschematically in the accompanying drawings, in which:

FIG. 1 is a perspective view of a particularly preferred design of acollet according to the invention;

FIG. 2 is a schematic side view of the collet from FIG. 1; and

FIG. 3 shows a particularly preferred design of a seal for use in thepreviously shown collet in a sectional view (A) and in a plan view (B).

FIG. 1 is, by way of example, a perspective view of a particularlypreferred design of a tensile clamp according to the invention, e.g.double cone clamps. Although the invention is explained in greaterdetail with reference to this specific kind of collet, the invention isin principle suitable for any kind of collet or guide clamp. Although anelement that holds the collets together is not shown for reasons ofclarity, it goes without saying that, for this purpose, the clampingjaws must be movable with respect to one another but must not come apartcompletely.

The collet 10 shown comprises a plurality of, namely three, clampingjaws 20 which are movable with respect to one another. The gap formedbetween each of the clamping jaws 20, which gap is formed between twoside faces of adjacent clamping jaws 20, is sealed on all sides by aseal 30 in each case, and therefore chips produced during machiningcannot enter the gap.

The seal 30 is, as shown in FIG. 2, fastened to the collet 10 by thefastening portions 32 engaging in the recesses 22 arranged in the sidefaces of adjacent clamping jaws 20.

In the example shown, the fastening portions 32 are designed inparticular as cylinders which are resilient at least in the direction oftheir longitudinal axis and therefore have spring-loading properties. Inthis particularly preferred embodiment, the fastening portions 32therefore replace the screw springs that are conventionally usedaccording to the prior art.

Finally, FIG. 3 shows the particularly preferred design of the seal 30in a sectional view (A) and in a plan view (B). The seal ismirror-symmetric in particular with respect to the gap plane between theclamping jaws 20 and has a sealing lip 34 which extends on both sides ofthe gap plane or on both sides of the seal 30.

The sealing lip 34 in particular extends around the seal 30. Additionalsealing lips (not shown) can be arranged within the circumferenceoccupied by the sealing lip 34, which additional sealing lips canoptionally prevent chips which have passed the sealing lip 34 frompenetrating into the recesses 22 of the clamping jaws. For this purpose,the fastening portions 32 can in particular be surrounded by anadditional sealing lip protecting the cylindrical portion thereof.

The present invention is suitable in particular for retrofittingexisting collets, whether these have screw springs or leaf springs,provided that their clamping jaws have a recess for fastening thesprings. In addition, the invention is of course also suitable forproducing new collets according to the invention.

1. Collet comprising a plurality of clamping jaws which can be movedwith respect to one another, at least one recess provided in one of themutually facing side faces of adjacent clamping jaws, in each case, aspring inserted into a recess which resiliently loads the adjacentclamping jaws with respect to one another, and a seal sealing the gap ineach case between two side faces of adjacent clamping jaws, the sealhaving a fastening portion (32) engaging in the at least one recess,wherein the fastening portion is designed as a hollow cylinderaccommodating the spring.
 2. (canceled)
 3. Collet according to claim 1,characterized in that the fastening portion is designed as a spring. 4.Collet according to claim 1, characterized in that the fastening portionis designed as a resilient cylinder.
 5. Collet according to claim 1,characterized in that the outer contour of the seal corresponds to theouter profile of the side faces of the clamping jaws.
 6. Colletaccording to claim 1, characterized in that the seal fully fills the gapbetween two side faces of adjacent clamping jaws.
 7. Collet according toclaim 1, characterized in that the seal comprises a sealing lipextending from the plane of the seal.
 8. Collet according to claim 7,characterized in that the sealing lip is arranged on the edge of theseal.
 9. Collet according to claim 1, characterized in that the seal ismirror-symmetric with respect to the gap plane between the clampingjaws.
 10. Collet according to claim 1, characterized by three clampingjaws.